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Identification Of A "Congested Area" Under FAR § 91.119: Hindsight Is 20/20

By Gregory J. Reigel

© September, 2008 All rights reserved.

The primary issue in a recent NTSB decision, Administrator v. Folk, was whether the airmen's low-level flights occurred over a "congested area" as referenced in FAR § 91.119. Although this case arose in the context of an aerial applicator operation, it is instructive for FAR Part 91 general aviation operations as well.

The Regulation

As you may recall, FAR § 91.119 delineates the minimum safe altitudes for operations under FAR Part 91: Over a "congested area" of a city, town, or settlement, an aircraft must operate 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft (§ 91.119(b)); and over other than congested areas, an aircraft must operate 500 feet above the surface, unless it is over open water or sparsely populated areas, in which case the aircraft must stay at least 500 feet away from any person, vessel, vehicle, or structure (§ 91.119(c)).

This regulation first appeared in the Air Commerce Regulations of 1926. The purpose of the rule is to provide minimum safe altitudes for flight and to provide adequate protection to persons on the ground. Unfortunately, neither the FAA nor the NTSB has ever provided airmen with a precise definition of what constitutes a "congested area." Rather, a "congested area" is determined on a case-by-case basis. According to the Board, "the determination must take into consideration all circumstances, not only the size of an area and the number of homes or structures, but, for example, whether the buildings are occupied or people are otherwise present, such as on roads."

Multiple legal interpretations issued by the FAA's Office of the Chief Counsel have also addressed this issue and reiterated the "case-by-case" analysis used to determine whether an area is congested. Size of the area is not controlling, and violations of the rule have been sustained for operation of aircraft: (i) over a small congested area consisting of approximately 10 houses and a school; (ii) over the campus of a university; (iii) over a beach area along a highway; and (iv) over a boy's camp where there were numerous people on the docks and children at play on shore. The legal interpretations have noted that the presence of people is important to the determination of whether a particular area is "congested." Thus, large, heavily congested residential areas of a city, town, or settlement would be considered "congested areas."

The Case

In the Folk case, the FAA alleged that the airmen had both engaged in agricultural aircraft operations in violation of 14 C.F.R. §§ 137.51(b)(1) through (3)2 (limitations on private agricultural aircraft operator); 91.119 (minimum safe altitudes); and 91.13(a) (careless and reckless). One of the main disputes in the case was whether the area over which the airmen had flown was a "congested area." At the hearing, the FAA argued that its case-by-case analysis of the facts and circumstances supported the conclusion that the area was indeed a "congested area." One of the airmen's arguments in response to the FAA's position was that the logical extension of the FAA's position that congested area determinations are made on a case-by-case basis is that nobody can know whether or not an area is congested until after their case has been decided.

During the hearing, the FAA inspector who investigated the allegations regarding the airmen testified that "if an operator conducts an application in an area the FAA might later determine to be a congested area, the operator ignores that potentiality at his or her peril." The inspector went on to say that he had warned the airmen that the area around their farm could be considered a congested area. When the airmen requested a definition of "congested area," the inspector told them there was no definition, and referred the airmen to FAA guidance, including an inspectors’ handbook. After studying the regulations and, apparently, finding no examples in the handbook that applied to their operations, the airmen then decided the area around their farm was not congested.

Unfortunately for the airmen, the ALJ agreed with the FAA. He concluded that the area over which the airmen had flown contained upwards of 30 homes, buildings, and structures and, as a result, was a "congested area." The ALJ also rejected a number of other defenses raised by the airmen and held that the airmen violated the regulations as alleged.

On appeal, the airmen renewed their argument that the area over which they had flown was not a "congested area." Initially, the Board observed that the FAA "has not pronounced a precise definition that includes the factors of the density of the population in an area; whether there is surface traffic in the vicinity; or the numbers and proximity of residences, buildings, or structures." It went on to note that "it is clear that the intent of the regulations is to protect persons and property on the ground and to fairly apply the rules to operators of aircraft, and, in the case of Part 137, to operators of agricultural aircraft." The Board then affirmed the ALJ's determination that the area over which the airmen had operated was a "congested area."

If you are like me, you are wondering "how am I supposed to know what constitutes a "congested area" if the FAA won't tell me?" Interestingly, Board member Hersman's dissent, although not determinative in the case, addresses this question and provides some pointed commentary on how the FAA could have avoided this dispute and how it could avoid such disputes in the future. She states that "this controversy could have been resolved (eliminating the many hours of work by all parties in appellate process) had the operators received from FAA more directive instructions about what the regulatory agency expected." She goes on to observe that "what constitutes congestion is dynamic and highly subjective" and "[i]f the FAA believes an area is congested, thus generating certain expectations of agricultural air operators operating there, the agency should make those expectations clearly known from the beginning and avoid a legal dispute that leads to license suspension followed by a lengthy and expensive appeals process."


So what does this mean to an FAR Part 91 operator? For most airmen, this regulation raises little concern. They take off, climb to their enroute altitude and later descend and land at their destination. However, airmen who enjoy flying "low and slow" or who want to "get a closer look" need to keep this regulation in mind during those operations.

Fortunately, the ball isn't completely hidden by the FAA's and NTSB's lack of a specific definition for "congested area." We do have previously decided cases in which this issue has been determined that provide some guidance. At the end of the day, how low you can go will depend upon the type of area over which you are flying. Hopefully your analysis of the area over which you fly will correspond with the 20/20 hindsight exercised by the FAA and NTSB.

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